The goal of this proposal is to expand the use of a novel C. elegans tissue-model of radiation-induced reproductive cell death ("Radelegans") to better define the genetic basis of the radioresponse. Reproductive cell death is the primary form of target "clonogen" cell death after radiotherapy, and Radelegans is the first in vivo model of reproductive cell death in isolation of other forms of cell death, allowing the genetic dissection of the radiation response. This work is the natural expansion of Radelegans (designed by the principal investigator) in a direction that will allow the creation of interesting hypothesis as well as the potential for meaningful discoveries in the field of cancer biology. The specific aims of this proposal are to develop Radelegans into a high-throughput screen (HTS) using RNAi (RNA interference) to allow evaluation of individual genes in the tissue and tumor-responses to radiation therapy. Concurrently, Radelegans will be used to evaluate the role of microRNA (miRNA) genes, global gene regulators, in the radiation response. Identifying the components of the complex genetic networks required for the radioresponse as well as the interaction of global gene regulators with these pathways will be a critical advance in our understanding of tissue and tumor-responses to cytotoxic therapy. This work also has the potential to identify not only new individual gene targets able to modulate the radioresponse, but also perhaps will enable the discovery of a novel and perhaps more efficacious class of modulators of cytotoxic therapy, miRNAs. This project will take place at Yale University, with outstanding core facilities and supporting faculty critical for guidance to obtain these goals. Course work in statistics as well as experimental design will also be pursued to give the principal investigator a solid foundation to interpret complex experimental results and design statistical analysis to bring together the extensive data generated by both the HTS as well as the miRNA analysis approaches. Over 700,000 people with cancer are treated with radiation therapy every year. A better genetic understanding of how tissues respond to radiation is critical to enable better protection of normal tissues as well as to enhance tumor cure. This work will use a novel model, Radelegans, to identify single-gene targets as well as test the potential of newly identified gene regulators (microRNAs) to accomplish these goals.